In a conventional liquid crystal display panel, liquid crystals are contained between two sheets of glass substrate. For a thin film transistor panel (TFT) type panel, a color filter, a transparent electrode and a thin film transistor are formed on surfaces of glass substrates and a gap between the glass substrates is maintained at a substantially constant distance by spacers.
Liquid crystal material between the substrates is hermetically sealed between the panels by a thermosetting resin. In manufacturing a liquid crystal display panel, a seal is provided between the sheets that contains the liquid crystals. Thereafter uniting the two sheets of the glass substrate creates a fused element. According to the process, in the display area, the seal is cured while being compressed. The spacers are brought into contact with the two glass substrates provide a uniform gap therebetween.
After curing of the seal, the sealed area is filled with liquid crystal material. When a thermosetting resin is used for the seal, according to conventional technology, the gap between the two sheets of glass substrates is made mainly by the following three systems: (1) a system of sandwiching and pressing the glass substrates with two flat heaters, (2) a system of placing the glass substrates in a pressure chamber and using the pressure difference between atmospheric pressure and a vacuum created by exhausting air from between the plates, and heating the glass substrates with a heater provided on the plate or with a furnace, and (3) a system of sandwiching the glass substrates with airtight sheets from both sides thereof pressing the glass substrates in a pressure chamber, as in the second method, and heating the glass substrates in a furnace. All of these are systems were developed to promote uniformity of the compressive force and for the two sheets of the glass substrates to be heated at the same temperature.